1. Field of the Invention
The present invention relates to an air compressor, and more particularly to an air compressor comprising an improved connecting portion through which air is supplied from a compressing section to a pulsation-absorbing tank.
2. Description of the Related Art
Among various conventional air compressors, there is a type disclosed in Published Unexamined Japanese Utility Model Application (PUJUMA) No. 59-167976. FIG. 4 is a sectional view of the air compressor disclosed in this reference.
As is shown in FIG. 4, casing 3 in which both air-compressing section 1 and pulsation-absorbing tank 2 are arranged is made up of upper casing 3a, lower casing 3b, and cover 3c. Filter 7 is placed on the top of upper casing 3a, and is secured to upper casing 3a by cover 3c.
Lower casing 3b is fitted into upper casing 3a, and the fitted portion is hermetically sealed with sealant 8.
A plurality of supporting members 4 formed of an elastic material are arranged in lower casing 3b. Compressing section 1 is fixed to the tops of supporting members 4, and pulsation-absorbing tank 2 is fixed to longitudinally intermediate points of supporting members 4. In this manner, compressing portion 1 and pulsation-absorbing tank 2 are isolated from each other and are individually coupled to casing 3 through elastic supporting members 4. Therefore, vibration of compressing section 1 and that of pulsation-absorbing tank 2 are not transmitted directly to casing 3.
Compressing section 1 includes cylinder 10, and piston 11 which reciprocates inside cylinder 10. The air purified by filter 7 is supplied into the interior of compressing section 1 through air inlet port 14, and is compressed by the reciprocating motion of piston 11. After compression, the air is supplied into annular region 12 located around cylinder 10 by way of a discharge valve (not shown), and is then discharged into the exterior of compressing section 1 through discharge port 5.
The air discharged from compressing section 1 passes through connecting hose 6 and is supplied into pulsation-absorbing tank 2 by way of air-introducing port 9. The pulsating flow of the air compressed by compressing section 1 is absorbed by tank 2, so that smoothly-flowing compressed air can be obtained from air outlet port 15.
Connecting hose 6 mentioned above is fastened to both discharge port 5 and air-introducing port 9 by clamping rings 13.
Cushion 16 is adhered to the inner wall of upper casing 3a. By this cushion 16, casing 3 is prevented from contacting compressing section 1 even it is exerted with external force.
In regard to the construction and operating principles, compressing section 1 is similar to the compressing sections described in Published Examined Japanese Patent Applications (PEJPAs) No. 57-32226 and No. 57-30984. Therefore, a description of the construction and operating principles of compressing section 1 will be omitted herein.
The conventional air compressor mentioned above has the following problems:
In order to prevent vibration of compressing section 1 from being transmitted to pulsation-absorbing tank 2, connecting hose 6 (which connects discharge port 5 of compressing section 1 and air-introducing port 9 of tank 2 together) is formed of an elastic material, such as rubber. The ends of this hose 6 have to be fastened to discharge port 5 and air-introducing port 9, respectively, by clamping rings 13. It should be noted that this hose-fastening operation is troublesome to perform. In the case of mass production of air compressors, such a hose-fastening operation lengthens the fabrication time and is a laborious work to those engaged in the fabrication of the air compressors.
In order to prevent the air-passing noise from leaking from the interior of hose 6, this hose 6 should have a certain thickness. For example, the thickness of hose 6 should be 2 mm or more. However, if hose 6 has a great thickness, it inevitably becomes rigid, so that the initial intention of employing hose 6 (i.e., to prevent the vibration of compressing section 1 from being transmitted to pulsation-absorbing tank 2) is not attained. In order to attain the initial intention, hose 6 should not have a great thickness but should be extended. Alternatively, it should be provided with a complex-shape vibration-absorbing portion at an intermediate point thereof.